I own a late-2013 15" Retina Macbook Pro and Big Sur "bricked" it in that at one point it kept booting and couldn't find its boot drive, and going into Internet Recovery showed that Disk Utility couldn't even see the boot drive as an attached device.
I contacted Apple Support through the Store app, and because I originally bought it with a business account, I got business support through Apple Messages. They went through the full diagnostic with me and all the resets and nothing worked. They booked an appointment for me with a local authorized repair shop.
I shut it down, unplugged it and let it sit that way for about 36 hours. After reading all the posts about it, I decided to try a bit more jiggery-pokery, and plugged it back in and turned it on, and it booted up into Big Sur. I've never seen anything like it. Hardware self-repairing? I'm assuming maybe a firmware update went through at the last minute? I have no idea.
It's not entirely fixed. It mostly works, but every couple of days if I don't fully shut down and power up again, it'll give me the spinning beach ball of doom and then go black screen and eventually turn off (or make me turn it off). I suspect I may need to replace its IO logic board. It's really weird that the same component keeps being the failure point. Almost like some slipstreamed firmware update in Big Sur is corrupting the hardware somehow?
My main issue with this problem is that APPLE SAID BIG SUR WAS SAFE WITH MY MODEL. If Apple hadn't said so, I would have happily trucked along with Catalina (my hardware was ROCK SOLID with Catalina) and budgeted for another MBP soon. But in saying that Big Sur was safe with this model, it set an expectation that the upgrade wouldn't completely screw up my Macbook Pro. That's the irresponsibility that I dislike, and it's what I think is at the root of the problem. After encouraging us to upgrade, and screwing up the hardware, Apple's acting like it's our fault for trying an upgrade that they said was safe and pushed notifications to us in Settings to go ahead and do.
I view this as a lapse in judgement for now. But if they just sweep it under the rug, that will seem negligent to me, bordering on fraudulent.